Is capitalism to blame?

In The Politically Incorrect Guide to Capitalism, Chapter 10, "Growing Pains," author Robert P. Murphy addresses the charge of theoretical Marxists who claim periodic depressions are an inescapable part of capitalism.  Writes Murphy:

The problem with this explanation is that there is nothing to distinguish booms from busts.  If free enterprise causes depressions, why did the worst one happen in the 1930s, rather than, say, the 1850s or the 1880s?  Certainly the American market was just as "wildcat" in those earlier decades. (p. 98)

Good point.